1. a) Field of the Invention
The present invention relates to a hot-melt type adhesive composition which is suitable for adhesion and sealing to metals without pretreatment and a non-slip processing method of metal scaffolding board.
More particularly, the invention relates to the hot-melt adhesive composition which can be preferably used for adhesion of plastics having difficulty on adhesion and sealing to metals, is excellent in adhesion properties to oiled surface of metals, resistance to water and corrosion, and is capable of conducting instant adhesion or short time adhesion. And the invention relates to the non-slip processing method of metal scaffolding board by using oiled-face adherable hot-melt adhesive without pretreatment.
2. b) Description of the Invention
A hot-melt adhesive composition having 100% solid content has conventionally been used in various fields, well known on its usefulness in industry, and employed in a rapidly increasing amount due to instant adhesion characteristic and freedom pollution.
Conventional arts for adhesives exhibiting adhesion properties to oiled surface have been known as thermosetting type adhesives, for example, an epoxy adhesive, solvent type adhesive and a two component acrylic adhesive. These adhesives substantially have problems of toxicity, odor and poor workability and hence conversion to a solventless type hot-melt adhesive composition is required.
However, a hot-melt adhesive which exhibits good adhesion properties to both the oiled surface of metals and non-polar plastics has not yet been found.
In the field of automotive assembly, particularly reliability in adhesion is regarded as important for the adhesion processing of steel plates or adhesion of various plastic parts for rigging. A liquid epoxy adhesive capable of oiled-face adhesion is used for the adhesion of face-oiled steel plates in a door hemming portion.
Hot-melt adhesives have recently been focused attention again for the adhesion of various plastic parts for rigging in view of pollution-free properties and increase in productivity. However, adhesives which can exhibit satisfactory adhesion properties to face-oiled materials have not yet been found.
In the field of building materials, for example, hot-melt adhesive is also coated on metallic scaffold plates in order to prevent slip. However, conventional adhesives can be applied to degreased materials alone and require complex coating steps. Development of hot-melt adhesive composition capable of adhering to oiled surface is strongly desired in view of pollution-free application and energy saving.
A hot-melt adhesive composition primarily composed of butyl rubber has been disclosed in Japanese Patent Publication 92379 (1985) as a pollution-free, instant adhesive or an adhere-sealing agent which is most suitable for plastics of difficult adhesion. Some of other hot-melt adhesive compositions have been known to contain thermoplastic macro molecule such as styreneethylene-butylene-styrene resin, styrene-butadienestyrene resin, and styrene-isoprene-styrene resin as a base polymer and other components such as tackifiers, waxes and plasticizers.
For adhesion of woods and papers in particular, many hot-melt adhesive compositions containing ethylenevinyl acetate resin as thermoplastic macro molecule have been known. On the other hand, disclosed arts for hot-melt adhesive compositions capable of adhering metals include polyamide base, polyester base, ethylene-vinyl acetate base and rubber base hot-melt compositions. Any of these adhesive compositions, however, have exhibited adhesion reliability only on a clean surface of metals. Oiled metal surface having build-up of cutting oil, lubricant or rust proof oil can not at all or scarcely exhibit adhesive force as such by the conventional hot-melt adhesive composition.
Consequently, in the case of adhering metals by using conventionally known hot-melt adhesive compositions, it has been required, for example, to previously conduct degreasing treatment, or to carry out flame treatment for degreasing and preheating, or to use a specific primer.
As mentioned above, there are following four requirements in the market.
The first requirement is to provide a hot-melt adhesive composition having excellent adhesion to oiled surface without pretreatment by utilizing instant adhesion properties of the hot-melt adhesive.
The second requirement is to provide reliability for adhesion to, for example, polypropylene, acrylics, polyethylene, polycarbonate, acrylonitrile-styrene resin, acrylonitrile-butadiene-styrene resin and other plastics which are difficult to adhere.
The third requirement is to provide the adherend with water resistance and environmental compatibility.
The fourth requirement relates to the above third requirement, and is to provide rust prevention for metals, that is, to provide a hot-melt adhesive composition having high rust-preventive effect after adhesion.